<?php 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

require_once ("database.php");

/** 
 * This class gives implementation of MSSQL database
 */
class MSSQLDatabase extends Database
{
	/**
	 * handle to the database
	 */
	protected $dbhandle;

	/**
	 * Connection informations
	 */
	public $connectionInfo;

	/**
	 * Constructor
	 * @param connectioninfo
	 */
	public function MSSQLDatabase($connInfo)
	{
		$this->connectionInfo = $connInfo;	
	}

	/**
	 * This method establishes a connection to the database. 
	 * @return boolean, upon successfull execution true is returned. 
	 * Otherwise false will be returned. 
	 */
	public function ConnectToDatabase()
	{
		if ($this->connectionInfo != NULL)
		{
			$this->dbhandle = sqlsrv_connect( $this->connectionInfo->server,
							    array( "Database" => $this->connectionInfo->database,
								       "UID" => $this->connectionInfo->user,
								       "PWD" => $this->connectionInfo->password,
								       "MultipleActiveResultSets" => 0 ) )
				or die ("Couldn't connect to the server!!!");
		}
		return true;
	}

	/**
	 * This method close the connection that is established to the
	 * database.
	 */
	public function CloseDatabase()
	{
		sqlsrv_close($this->dbhandle);
	}

	/**
	 * This method executes a query that it receives.
	 * @param query the query to execute
	 * @return non-NULL upon success and NULL otherwise.
	 */
	public function ExecuteQuery($query)
	{
		return sqlsrv_query( $this->dbhandle, $query );
	}

	/**
	 * This method returns the a value from a sql result set (a tuple
	 * returned after execution of ExecuteQuery method.
	 * @param result, the result obtained from ExecuteQuery method.
	 * @return the value at (raw, column) of the tuple.
	 */
	public function GetSQLValue($result)
	{		
		return sqlsrv_fetch_array($result);				
	}

	/**
	 * Gets the ID of the last inserted record. returns -1 if error. 
	 */
	public function GetInsertID()
	{
		$result = $this->ExecuteQuery("SELECT @@identity");
		if(!$result)
		{
			return -1;
		}
		else
		{
			$dbval = $this->GetSQLValue($result);
			return $dbval[0];
		}
	}

	/**
	 * Begin a transaction. return status will be not null if success
	 */
	public function BeginTransaction()
	{
		return $this->ExecuteQuery("BEGIN TRAN");
	}

	/**
	 * Commit a transaction.  return status will be not null if success
	 */
	public function CommitTransaction()
	{
		return $this->ExecuteQuery("COMMIT TRAN");
	}

	/**
	 * Rollback a transaction. return status will be not null if success
	 */
	public function RollbackTransaction()
	{
		return $this->ExecuteQuery("COMMIT TRAN");
	}
}
?>